CN101598803B - Method for directly obtaining stacked section of converted wave - Google Patents

Abstract

The invention relates to a method for directly obtaining the stacked section of a converted wave in multi-wave multi-component seismic data processing. The method comprises the following steps: reading parameters of equivalent velocity, and the like of the converted wave; calculating common conversion point numbers of sample points in each time window; recovering accurate ratio of the equivalent velocity, the velocity of a transverse wave and the velocity of a longitudinal wave of each sample point according to the common conversion point numbers of the sample points; recalculating relatively accurate common conversion point numbers of each time window; directly stacking sample point values in each time window on a width with the section being common-reflection surface area element of the converted wave; and obtaining the stacked section of the converted wave by dividing the corresponding covering times of the sample point values by each of the sample point value on the stacked section. The invention avoids complex calculation, has convenient application and favorable maintenance of the obtained seismic section wave field, can be directly used for seismic data interpretation and can be used for the analysis of converted wave velocity.

Description

A kind of method that directly obtains stacked section of converted wave

Technical field

The present invention relates to the petroleum exploration technology, is a kind of method that directly obtains stacked section of converted wave in the multiwave multicomponent earthquake Data Processing.

Background technology

Many components transformed wave seismic technology had both had that the longitudinal wave exploration degree of depth is big, data collection is relatively easy and the characteristics of small investment, can reflect that again the shear wave velocity of underground medium changes.These characteristics of many components transformed wave earthquake make the Direct Recognition of lithology exploration and oil gas become possibility.In the transformed wave communication process, descending wave path and upward traveling wave path do not have symmetry.Altogether the position of transfer point is relevant with the ratio of geophone offset, reflection horizon speed and longitudinal and transverse wave velocity, and the basic assumption that common midpoint is that this compressional wave of common reflection point handles can't be set up in transformed wave is handled.The calculating of transfer point is the basis of transformed wave stack and imaging altogether, and existing technology is that acquisition stacked section of converted wave again superposes on the basis of extracting CRP gather.The transfer point stack is a gordian technique during transformed wave is handled altogether, directly influences final transformed wave imaging precision and seismic data interpretation.

Summary of the invention

The present invention provides a kind of method that directly obtains stacked section of converted wave fast and effectively.

The present invention realizes by following concrete steps:

1) gather original conversion rolling land shake data, through pre-service and velocity analysis, obtain the transformed wave velocity equivalent, p-and s-wave velocity such as compares at parameter;

The described pre-service of step 1) comprises the loading recording geometry, static correction, and wave field separation, the prestack denoising, common transfer point (CCP) number is preset in amplitude restoration.

2) number read parameters such as transformed wave velocity equivalent by the common transfer point (CCP) in the first road earthquake data before superposition trace header;

3) the timesharing window calculate this road each the time window in the common transfer point (CCP) number of sampling point, according to the common transfer point (CCP) of each sampling point number, regain each sampling point of this road transformed wave velocity equivalent and p-and s-wave velocity ratio accurately again;

The described timesharing window of step 3) calculate this road each the time window in the method for common transfer point (CCP) number of sampling point be that this road is divided into window when a plurality of, the time window number=road length/window length, the time window not overlapping, the common transfer point (CCP) of all sampling points number in window when central point calculates this in the window on time;

Described transformed wave velocity equivalent of step 3) and p-and s-wave velocity are than being the transformed wave root-mean-square velocity that velocity analysis in advance obtains

, the compressional wave root-mean-square velocity

, anisotropic parameters k _EffCompare r with p-and s-wave velocity;

The described altogether transfer point (CCP) of step 3) number is meant by the work area binning, and is number consistent with compressional wave common midpoint (CMP) in the conventional processing;

The described altogether transfer point (CCP) of step 3) number is calculated by following method:

x _C＝x _M+D (1)

X in the formula _M, x _CBe the horizontal coordinate of common midpoint (CMP) and common transfer point (CCP) point, D is the horizontal range of transfer point off-center point

$D=x_p-\frac{x}{2}---\left(2\right)$

X in the formula _pBe total to the horizontal range between transfer point and the shot point,

Known common midpoint (CMP) number

, calculate corresponding transfer point (CCP) altogether number

$j_{x_C}={\mathrm{INT}}_n\left(\frac{x_C}{\mathrm{\Δ}{x}_m}\right)$

$={\mathrm{INT}}_n\left(\frac{x_M+D}{{\mathrm{\Δx}}_m}\right)---\left(3\right)$

$=j_{x_M}+{\mathrm{INT}}_n\left(\frac{D}{{\mathrm{\Δx}}_m}\right)$

Wherein: INT _nImmediate integer is got in expression, rounds implicit do bin processing, Δ x _mBe work area bin size,

Horizontal range between described altogether transfer point of step 3) and the shot point, when adopting iterative solution formula (7) to calculate, in the iterative computation process, whole road first the time window in the x of sampling point _pInitial value adopts formula (6), the x of window when the initial value of sampling point adopts in the window when next _p,

Initial value $x_{p0}=\frac{x\·r}{1+r}---\left(6\right)$

$x_p=\frac{\sqrt{1+{\left(\frac{x_p}{z}\right)}^2(1-r^2)}}{r+\sqrt{1+{\left(\frac{x_p}{z}\right)}^2(1-r^2)}}---\left(7\right)$

Wherein, x _pBe the horizontal range between common transfer point and the shot point, r is the p-and s-wave velocity ratio, and z is the degree of depth of reflecting interface $z=\frac{\sqrt{r}}{1+r}\·t_{0\mathrm{ps}}\·v_c.$

4) accurate transformed wave velocity equivalent and the anisotropic parameters that obtains with step 3) carries out normal moveout correction to this road;

The described moving effect of step 4) adopts the anisotropy 4 rank transformed wave T-X curve normal moveout correction formula of simplification just:

$t_{\mathrm{ps}}^2=t_{0\mathrm{ps}}^2+\frac{x^2}{v_c^2}-2k_{\mathrm{eff}}\frac{x^4}{v_c^2[t_{0\mathrm{ps}}^2{v}_c^2+4k_{\mathrm{eff}}{x}^2]}---\left(4\right)$

In the formula, v _cThe NMO velocity of transformed wave, x are offset distance, and promptly shot point is to the horizontal range of geophone station, t _PsThe expression travel-time of transformed wave when geophone offset x,

The expression transformed wave round trip vertical transmission time.

5) transformed wave velocity equivalent and the p-and s-wave velocity ratio that obtains with step 3), the relatively accurate common transfer point (CCP) of window number when recomputating each, sample value during directly each in the window is stacked on the section, and promptly on the width of transformed wave common reflection surface, degree of covering increases by 1 on the corresponding section;

Step 5) is described, and transfer point (CCP) number computing method are identical with step 3) altogether;

Step 5) described during directly each the sample value in the window be stacked on the section, be during this sampling point in window be superimposed upon accurately altogether transfer point (CCP) number (

) on, and adjacent I is altogether on the transfer point (CCP) number, and I=0,1,2 ..., INT (2m/ Δ x+0.5), m is the width of transformed wave common reflection surface, INT represents to round;

The width of the described transformed wave common reflection surface of step 5) adopts following relational expression to determine:

$m=\left\{\begin{array}{cc}1& \mathrm{\&Delta;m}=0\\ [1/(1-\mathrm{\&Delta;m})+0.5]& \mathrm{\&Delta;m}\&GreaterEqual;0.5\\ [1/\mathrm{\&Delta;m}+0.5]& \mathrm{\&Delta;m}<0.5\end{array}\right.---\left(5\right)$

$\mathrm{\&Delta;m}=\frac{(1+r)\&CenterDot;\mathrm{\&Delta;s}}{r\&CenterDot;\mathrm{\&Delta;x}}-\mathrm{INT}\left[\frac{(1+r)\&CenterDot;\mathrm{\&Delta;s}}{r\&CenterDot;\mathrm{\&Delta;x}}\right]$

Wherein: Δ x is a track pitch, and Δ s is a shot interval, and r is the p-and s-wave velocity ratio, and INT represents to round;

Step 5) described each the time window, window when being meant each that step 3) divides, the time window overlapping, the number percent (perc) of number of samples in the window when overlap length of window is when overlapping, the perc value is 0-50.

6) repeating step 2) to 5) finish up to all input channel stacks, each sample value on the stacked section obtains the stacked section of transformed wave divided by its corresponding degree of covering.

The present invention needn't extract CCP road collection earlier, superpose again, can obtain stacked section of converted wave accurately, avoided complicated calculating, it is convenient to use, and the seismic section wave field that obtains keeps, can directly carry out seismic data interpretation, and can be used for the transformed wave velocity analysis, and carry out quality monitoring, effectively determine transformed wave velocity equivalent, p-and s-wave velocity ratio and anisotropic parameters.

Description of drawings

Fig. 1 is a transformed wave propagation rays of the present invention path synoptic diagram;

Fig. 2 is an embodiment of the invention stacked section of converted wave.

Concrete embodiment

Of the present invention is the method that directly obtains stacked section of converted wave, by reading CCP number that presets in the trace header, obtain the information such as speed in the parameter field, direct timesharing window calculates CCP number of this each sampling point of road, upgrade the information such as speed in this road once more from parameter field, normal moveout correction is carried out the playback of lineups level then, recomputate this road each the time CCP number of window, directly fold out stacked section.

The horizontal range that the present invention calculates between common transfer point and the shot point realizes that principle is as follows:

(1) under the uniform dielectric condition, when determining the location aware of transfer point, derive the iterative solution of position of conversion point:

Initial value $x_{p0}=\frac{x\&CenterDot;r}{1+r}---\left(6\right)$

$x_p=\frac{\sqrt{1+{\left(\frac{x_p}{z}\right)}^2(1-r^2)}}{r+\sqrt{1+{\left(\frac{x_p}{z}\right)}^2(1-r^2)}}---\left(7\right)$

Wherein, x _pBe the horizontal range between common transfer point and the shot point, r is the p-and s-wave velocity ratio, and z is the degree of depth of reflecting interface.

And: $z=\frac{\sqrt{r}}{1+r}\&CenterDot;t_{0\mathrm{ps}}\&CenterDot;v_c---\left(8\right)$

Calculate the method for the horizontal range between the transfer point and shot point altogether, in the iterative computation process, whole road first the time window in the x of sampling point _pInitial value adopts formula (6), the x of window when the initial value of sampling point adopts in the window when next _p, this method has reduced iterations greatly, has improved counting yield.

(2) under the multilayered medium condition, the common transfer point approximate solution of using Thomsen (1999) to derive:

$x_p\&ap;x[c_0+c_2\frac{{\left(\frac{x}{t_{0\mathrm{ps}}{v}_{c_2}}\right)}^2}{1+c_3{\left(\frac{x}{t_{0\mathrm{ps}}{v}_{c_2}}\right)}^2}]---\left(9\right)$

$c_0=\frac{{\mathrm{\&gamma;}}_{\mathrm{eff}}}{1+r_{\mathrm{eff}}},$ $c_2=\frac{{\mathrm{\&gamma;}}_{\mathrm{eff}}({\mathrm{\&gamma;}}_{\mathrm{eff}}{\mathrm{\&gamma;}}_0-1)(1+{\mathrm{\&gamma;}}_0)}{2{\mathrm{\&gamma;}}_0{(1+{\mathrm{\&gamma;}}_{\mathrm{eff}})}^3},$ $c_3=\frac{c_2}{1-c_0}---\left(10\right)$

T in the formula _OpsWith

Be transformed wave round trip vertical transmission time and root-mean-square velocity, γ _EffBe effective p-and s-wave velocity ratio.

Ripple vertical velocity ratio in length and breadth

${\mathrm{\&gamma;}}_0=\frac{v_p^2}{v_{\mathrm{ps}}^2}---\left(11\right)$

In the formula, v _pBe the equal speed of P popin, v _PsBe transformed wave average velocity.

Under the layered medium condition, the root-mean-square velocity of known P ripple and PS ripple

With , effective p-and s-wave velocity ratio

${\mathrm{\&gamma;}}_{\mathrm{eff}}=\frac{v_{p_2}^2}{(1+{\mathrm{\&gamma;}}_0)v_{c_2}^2-v_{p_2}^2}---\left(12\right)$

Describe the embodiment of the invention in detail below in conjunction with accompanying drawing.

(1) the transformed wave source book of being gathered is carried out pre-service, carried out the compressional wave processing, obtained velocity of longitudinal wave , again by formula (4) transformed wave carries out velocity analysis and obtains the transformed wave velocity equivalent

With anisotropic parameters k _Eff

(2) number be read as parameters such as transformed wave velocity equivalent by the common transfer point (CCP) in the first road earthquake data before superposition trace header;

(3) zone of interest position under the base area, window when seismic trace is divided into 10, seismologic record is 5 seconds, sampling interval is 4 milliseconds, each the time number of samples in the window be 125, the timesharing window calculate this road each the time window in the common transfer point (CCP) number of sampling point, each the time window common transfer point (CCP) number window mid-point computation during by each, again according to each sampling point transfer point (CCP) number altogether, iterative solution formula (7) is adopted in the calculating of position of conversion point altogether, regains each sampling point of this road transformed wave velocity equivalent and p-and s-wave velocity ratio accurately;

(4) accurate transformed wave velocity equivalent that obtains with step (3) and anisotropic parameters to this road by formula (4) carry out normal moveout correction;

(5) transformed wave velocity equivalent and the p-and s-wave velocity ratio that obtains with step (4), the relatively accurate common transfer point (CCP) of window center point number when recomputating each, iterative solution formula (7) is adopted in the calculating of position of conversion point altogether, adopt window when overlapping during stack, the number percent (perc=25) of number of samples in the window when overlap length of window is when overlapping, at this moment each the time number of samples in the window be 156, the sample value during directly each in the window be stacked in section (STACK ( , IT)) on, degree of covering on the corresponding section (FOLD (

, IT)) and increase by 1;

(6) repeating step (2) to (5) finishes up to the stack of all input channel, and ((CCP IT)/FOLD (CCP, IT)), obtains the stacked section of transformed wave to STACK to each sample value on the stacked section divided by its corresponding degree of covering.

According to above-mentioned concrete implementation step, obtained common transfer point stacked section (Fig. 2).

Claims (4)

1. method that directly obtains stacked section of converted wave is characterized in that realizing by following concrete steps:

1) gathers original conversion rolling land shake data, through pre-service and velocity analysis, obtain the transformed wave velocity equivalent, p-and s-wave velocity compares parameter;

Described pre-service comprises the loading recording geometry, static correction, and wave field separation, the prestack denoising, amplitude restoration is preset common transfer point CCP number;

2) read transformed wave velocity equivalent parameter by common transfer point CCP number in the first road earthquake data before superposition trace header;

3) the timesharing window calculate this road each the time window in common transfer point CCP number of sampling point, again according to common transfer point CCP number of each sampling point, regain each sampling point of this road transformed wave velocity equivalent and p-and s-wave velocity ratio accurately;

Transfer point CCP number is to be calculated by following method altogether:

x _C＝x _M+D (1)

X in the formula _M, x _CBe the horizontal coordinate that common midpoint CMP and common transfer point CCP are ordered, D is the horizontal range of transfer point off-center point

$D=x_p-\frac{x}{2}---\left(2\right)$

X in the formula _pBe the horizontal range between common transfer point and the shot point,

Known common midpoint CMP number

Calculate corresponding transfer point CCP number altogether

$j_{x_C}={\mathrm{INT}}_n\left(\frac{x_C}{\mathrm{\&Delta;}{x}_m}\right)$

$={\mathrm{INT}}_n\left(\frac{x_M+D}{{\mathrm{\&Delta;x}}_m}\right)---\left(3\right)$

$=j_{x_M}+{\mathrm{INT}}_n\left(\frac{D}{{\mathrm{\&Delta;x}}_m}\right)$

Wherein: INT _nImmediate integer is got in expression, rounds implicit do bin processing, Δ x _mBe work area bin size;

Horizontal range between described altogether transfer point and the shot point, when adopting iterative solution formula (7) to calculate, in the iterative computation process, whole road first the time window in the x of sampling point _pInitial value adopts formula (6), the x of window when the initial value of sampling point adopts in the window when next _p,

Initial value $x_{p0}=\frac{x\&CenterDot;r}{1+r}---\left(6\right)$

$x_p=\frac{\sqrt{1+{\left(\frac{x_p}{z}\right)}^2(1-r^2)}}{r+\sqrt{1+{\left(\frac{x_p}{z}\right)}^2(1-r^2)}}---\left(7\right)$

Wherein, x _pBe the horizontal range between common transfer point and the shot point, r is the p-and s-wave velocity ratio, and z is the degree of depth of reflecting interface

Described transformed wave velocity equivalent and p-and s-wave velocity are than being the transformed wave root-mean-square velocity that velocity analysis in advance obtains

The compressional wave root-mean-square velocity

Anisotropic parameters k _EffCompare r with p-and s-wave velocity;

4) accurate transformed wave velocity equivalent and the anisotropic parameters that obtains with step 3) carries out normal moveout correction to this road;

Described moving effect adopts the anisotropy 4 rank transformed wave T-X curve normal moveout correction formula of simplification just:

$t_{\mathrm{ps}}^2=t_{0\mathrm{ps}}^2+\frac{x^2}{v_c^2}-{2k}_{\mathrm{eff}}\frac{x^4}{v_c^2[t_{0\mathrm{ps}}^2{v}_c^2+4k_{\mathrm{eff}}{x}^2]}---\left(4\right)$

In the formula, v _cBe the NMO velocity of transformed wave, x is an offset distance, and promptly shot point is to the horizontal range of geophone station, t _PsThe expression travel-time of transformed wave when geophone offset x, t _0psThe expression transformed wave round trip vertical transmission time;

5) transformed wave velocity equivalent and the p-and s-wave velocity ratio that obtains with step 3), relatively accurate common transfer point CCP number of window when recomputating each, sample value during directly each in the window is stacked on the section, and degree of covering increases by 1 on the corresponding section, and transfer point CCP computing method are identical with step 3) altogether;

Described during directly each the sample value in the window to be stacked on the section be on the width of transformed wave common reflection surface;

Described during directly each the sample value in the window be stacked on the section, be that the sampling point in the window is superimposed upon accurately transfer point CCP number altogether during this

On, and adjacent I is altogether on transfer point CCP number, and I=0,1,2 ..., INT (2m/ Δ x+0.5), m is the width of transformed wave common reflection surface, INT represents to round;

The width of described transformed wave common reflection surface adopts following relational expression to determine:

$m=\left\{\begin{array}{cc}1& \mathrm{\&Delta;m}=0\\ [1/(1-\mathrm{\&Delta;m})+0.5]& \mathrm{\&Delta;m}\&GreaterEqual;0.5\\ [1/\mathrm{\&Delta;m}+0.5]& \mathrm{\&Delta;m}<0.5\end{array}\right.---\left(5\right)$

$\mathrm{\&Delta;m}=\frac{(1+r)\&CenterDot;\mathrm{\&Delta;s}}{r\&CenterDot;\mathrm{\&Delta;x}}-\mathrm{INT}\left[\frac{(1+r)\&CenterDot;\mathrm{\&Delta;s}}{r\&CenterDot;\mathrm{\&Delta;x}}\right]$

Wherein: Δ x is a track pitch, and Δ s is a shot interval, and r is the p-and s-wave velocity ratio, and INT represents to round I=0,1,2 ..., INT (2m/ Δ x+0.5), m is the width of transformed wave common reflection surface;

6) repeating step 2) to 5) finish up to all input channel stacks, each sample value on the stacked section obtains the stacked section of transformed wave divided by its corresponding degree of covering.

2. the method that directly obtains stacked section of converted wave according to claim 1, it is characterized in that the described timesharing window of step 3) calculate this road each the time window in common transfer point CCP number method of sampling point be that this road is divided into window when a plurality of, the time window number=road length/window length, the time window not overlapping, when central point calculates this in the window on time in the window common transfer point CCP number of all sampling points.

3. the method that directly obtains stacked section of converted wave according to claim 1, it is characterized in that step 3) described altogether transfer point CCP number by the work area binning, consistent with compressional wave common midpoint in conventional processing CMP number.

4. the method that directly obtains stacked section of converted wave according to claim 1, it is characterized in that step 5) described each the time window, window when being meant each that step 3) divides, the time window overlapping, the number percent of number of samples in the window when overlap length of window is when overlapping, the number percent value is 0-50.

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